Mail not delivered to some external email addresses after server-name/domain change

Hi ISP-Config Team!

I experience a strange issue, where I don't have any clue, what might be the cause:

I changed the name/domain of my server recently according to your change-server-name tutorial for ISPConfig 3 and everything seems to be ok. Server-DNS records are correct, PTR-record is correct, settings in the respective server-config-files (according to tutorial) are correct, SSL-Protocols work, Email-Postifx service is working, mxtoolbox-diagnostic shows no error, I can log into webmail or setup emails in a local email client (e.g. Outlook) and send and receive emails using the new server-domain as Incoming-Outgoing server. (like it worked with the former server-name/domain)

But there are some external mail providers, which I cannot send emails to, like Outlook 365 email accounts or GMX.at / .net email accounts. And there are some external email-addresses/providers, which receive my emails from the domains hosted on my ISPConfig mailserver, like GMAIL, for instance.

I looked up the logs and found some strange things in the mail-queue log:

* (connect to name-of-outlook-emailaddress.mail.protection.outlook.com[104.47.0.36]:25: Connection timed out)
* (connect to mx00.emig.gmx.net[212.227.15.9]:25: Connection timed out)

For Gmail, there is no such entry.

Could you please give me a hint. I am completely lost at the moment.

Thank you very much in advance,
Johannes

 

If those mails are not delivered, they are returned to sender and should contain reason why delivery failed. What is that reason?
Also, do this:
https://www.howtoforge.com/community/threads/please-read-before-posting.58408/
Try following:

1. Keep running in a terminal window command: tail -f /var/log/mail.log
2. send an e-mail to some place you know that delivery fails
3. keep an eye on what happens in the terminal window at 1. to see what happens with that sent e-mail

Check if your IP-number is on a blacklist. For example mxtoolbox.com is a web tool for that.

 

This is the tail from the maillog when sending to an address, which doesn't receive:

Dec 23 19:10:57 server postfix/smtpd[30707]: disconnect from unknown[46.38.144.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Dec 23 19:11:13 server postfix/smtpd[28783]: connect from unknown[46.38.144.17]
Dec 23 19:11:20 server postfix/smtpd[28783]: warning: unknown[46.38.144.17]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
Dec 23 19:11:20 server postfix/smtpd[28783]: disconnect from unknown[46.38.144.17] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Dec 23 19:11:38 server postfix/smtpd[30707]: connect from unknown[46.38.144.32]
Dec 23 19:11:38 server postfix/smtpd[28783]: connect from unknown[46.38.144.57]
Dec 23 19:11:43 server postfix/smtpd[28783]: warning: unknown[46.38.144.57]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
Dec 23 19:11:43 server postfix/smtpd[28783]: disconnect from unknown[46.38.144.57] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Dec 23 19:11:45 server postfix/smtpd[30707]: warning: unknown[46.38.144.32]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
Dec 23 19:11:46 server postfix/smtpd[30707]: disconnect from unknown[46.38.144.32] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Dec 23 19:12:12 server postfix/smtps/smtpd[32690]: connect from p2003000633520034D8A4AA9A448CD7A8.dip0.t-ipconnect.de[2003:6:3352:34:d8a4:aa9a:448c:d7a8]
Dec 23 19:12:13 server postfix/smtps/smtpd[32690]: NOQUEUE: filter: RCPT from p2003000633520034D8A4AA9A448CD7A8.dip0.t-ipconnect.de[2003:6:3352:34:d8a4:aa9a:448c:d7a8]: <[email protected]>: Sender address triggers FILTER amavis:[127.0.0.1]:10026; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<JHLaptop>
Dec 23 19:12:13 server postfix/smtps/smtpd[32690]: 0DD77A07114: client=p2003000633520034D8A4AA9A448CD7A8.dip0.t-ipconnect.de[2003:6:3352:34:d8a4:aa9a:448c:d7a8], sasl_method=LOGIN, [email protected]
Dec 23 19:12:13 server postfix/cleanup[32693]: 0DD77A07114: message-id=<[email protected]>
Dec 23 19:12:13 server postfix/qmgr[19348]: 0DD77A07114: from=<[email protected]>, size=2989, nrcpt=1 (queue active)
Dec 23 19:12:13 server postfix/smtpd[32697]: connect from localhost[127.0.0.1]
Dec 23 19:12:13 server postfix/smtpd[32697]: 752A3A07116: client=localhost[127.0.0.1]
Dec 23 19:12:13 server postfix/cleanup[32693]: 752A3A07116: message-id=<[email protected]>
Dec 23 19:12:13 server postfix/smtpd[32697]: disconnect from localhost[127.0.0.1] ehlo=1 mail=1 rcpt=1 data=1 quit=1 commands=5
Dec 23 19:12:13 server postfix/qmgr[19348]: 752A3A07116: from=<[email protected]>, size=3943, nrcpt=1 (queue active)
Dec 23 19:12:13 server amavis[15028]: (15028-12) Passed CLEAN {RelayedOutbound}, ORIGINATING LOCAL [2003:6:3352:34:d8a4:aa9a:448c:d7a8]:50112 [2003:6:3352:34:d8a4:aa9a:448c:d7a8] <[email protected]> -> <[email protected]>, Queue-ID: 0DD77A07114, Message-ID: <[email protected]>, mail_id: UVkupdATO0tZ, Hits: -0.999, size: 2989, queued_as: 752A3A07116, dkim_new=cslkey:mail-id.com, 229 ms
Dec 23 19:12:13 server postfix/smtp[32694]: 0DD77A07114: to=<[email protected]>, relay=127.0.0.1[127.0.0.1]:10026, delay=0.51, delays=0.27/0.01/0/0.23, dsn=2.0.0, status=sent (250 2.0.0 from MTA(smtp:[127.0.0.1]:10027): 250 2.0.0 Ok: queued as 752A3A07116)
Dec 23 19:12:13 server postfix/qmgr[19348]: 0DD77A07114: removed
Dec 23 19:12:14 server dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=2003:6:3352:34:d8a4:aa9a:448c:d7a8, lip=2a04:2180:0:2::166, mpid=32701, TLS, session=<e9QBIWKawsMgAwAGM1IANNikqppEjNeo>
Dec 23 19:12:15 server dovecot: imap-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=2003:6:3352:34:3899:8eae:d2a:d187, lip=2a04:2180:0:2::166, TLS, session=<DSoKIWKaZrcgAwAGM1IANDiZjq4NKtGH>
Dec 23 19:12:15 server postfix/qmgr[19348]: EA3CFA0709D: from=<[email protected]>, size=9146, nrcpt=1 (queue active)
Dec 23 19:12:15 server postfix/qmgr[19348]: 9CFF8A070B9: from=<[email protected]>, size=9121, nrcpt=1 (queue active)
Dec 23 19:12:15 server postfix/qmgr[19348]: 8E228A070BA: from=<[email protected]>, size=9121, nrcpt=1 (queue active)
Dec 23 19:12:15 server postfix/qmgr[19348]: 8EAD4A07115: from=<[email protected]>, size=3916, nrcpt=1 (queue active)
Dec 23 19:12:15 server postfix/qmgr[19348]: 77829A070DA: from=<[email protected]>, size=3956, nrcpt=1 (queue active)
Dec 23 19:12:15 server postfix/error[32703]: EA3CFA0709D: to=<[email protected]>, relay=none, delay=21470, delays=21470/0.01/0/0.01, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to outlook-emailaddress.mail.protection.outlook.com[104.47.0.36]:25: Connection timed out)
Dec 23 19:12:15 server postfix/smtps/smtpd[32690]: disconnect from p2003000633520034D8A4AA9A448CD7A8.dip0.t-ipconnect.de[2003:6:3352:34:d8a4:aa9a:448c:d7a8] ehlo=1 auth=1 mail=1 rcpt=1 data=1 quit=1 commands=6
Dec 23 19:12:15 server dovecot: imap-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=2003:6:3352:34:3899:8eae:d2a:d187, lip=2a04:2180:0:2::166, TLS, session=<MbcRIWKaEYogAwAGM1IANDiZjq4NKtGH>
Dec 23 19:12:16 server dovecot: imap-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=2003:6:3352:34:3899:8eae:d2a:d187, lip=2a04:2180:0:2::166, TLS, session=<RkoYIWKaC40gAwAGM1IANDiZjq4NKtGH>
Dec 23 19:12:24 server postfix/smtpd[28783]: connect from unknown[46.38.144.117]

I do not get back any bounce-emails. The IP-address of the server (ipv4 and ipv6) are not listed on any blacklist (checked by mxtoolbox).
PS: I anonymized the senders- & recipients emailaddresses.

 

And result of the htf-report:


##### SERVER #####
IP-address (as per hostname): ***.***.***.***
[WARN] could not determine server's ip address by ifconfig
[INFO] OS version is Ubuntu 18.04.3 LTS
[INFO] ISPConfig is installed.

##### ISPCONFIG #####
ISPConfig version is 3.1.15p2

##### VERSION CHECK #####

[INFO] php (cli) version is 7.2.24-0ubuntu***.***.***.***

##### PORT CHECK #####

##### MAIL SERVER CHECK #####

##### RUNNING SERVER PROCESSES #####

[INFO] I found the following web server(s):
Apache 2 (PID 20310)
[INFO] I found the following mail server(s):
Postfix (PID 19346)
[INFO] I found the following pop3 server(s):
Dovecot (PID 19358)
[INFO] I found the following imap server(s):
Dovecot (PID 19358)
[INFO] I found the following ftp server(s):
PureFTP (PID 19779)

##### LISTENING PORTS #####
(only ()
Local (Address)
[anywhere]:993 (19358/dovecot)
[anywhere]:995 (19358/dovecot)
[localhost]:10023 (981/postgrey)
[localhost]:10024 (2206/amavisd-new)
[localhost]:10025 (19346/master)
[localhost]:10026 (2206/amavisd-new)
[localhost]:10027 (19346/master)
[anywhere]:587 (19346/master)
[localhost]:11211 (1019/memcached)
[anywhere]:110 (19358/dovecot)
[anywhere]:143 (19358/dovecot)
[anywhere]:465 (19346/master)
***.***.***.***:53 (980/named)
[anywhere]:21 (19779/pure-ftpd)
[localhost]:53 (980/named)
***.***.***.***:53 (929/systemd-resolve)
[anywhere]:22 (1063/sshd)
[anywhere]:25 (19346/master)
[localhost]:953 (980/named)
*:*:*:*::*:993 (19358/dovecot)
*:*:*:*::*:995 (19358/dovecot)
*:*:*:*::*:10023 (981/postgrey)
*:*:*:*::*:10024 (2206/amavisd-new)
*:*:*:*::*:10026 (2206/amavisd-new)
*:*:*:*::*:3306 (1197/mysqld)
*:*:*:*::*:587 (19346/master)
[localhost]10 (19358/dovecot)
[localhost]43 (19358/dovecot)
*:*:*:*::*:8080 (20310/apache2)
*:*:*:*::*:80 (20310/apache2)
*:*:*:*::*:8081 (20310/apache2)
*:*:*:*::*:465 (19346/master)
*:*:*:*::*:21 (19779/pure-ftpd)
*:*:*:*::*:53 (980/named)
*:*:*:*::*:22 (1063/sshd)
*:*:*:*::*:25 (19346/master)
*:*:*:*::*:953 (980/named)
*:*:*:*::*:443 (20310/apache2)

##### IPTABLES #####
Chain INPUT (policy DROP)
target prot opt source destination
ufw-before-logging-input all -- [anywhere]/0 [anywhere]/0
ufw-before-input all -- [anywhere]/0 [anywhere]/0
ufw-after-input all -- [anywhere]/0 [anywhere]/0
ufw-after-logging-input all -- [anywhere]/0 [anywhere]/0
ufw-reject-input all -- [anywhere]/0 [anywhere]/0
ufw-track-input all -- [anywhere]/0 [anywhere]/0

Chain FORWARD (policy DROP)
target prot opt source destination
ufw-before-logging-forward all -- [anywhere]/0 [anywhere]/0
ufw-before-forward all -- [anywhere]/0 [anywhere]/0
ufw-after-forward all -- [anywhere]/0 [anywhere]/0
ufw-after-logging-forward all -- [anywhere]/0 [anywhere]/0
ufw-reject-forward all -- [anywhere]/0 [anywhere]/0
ufw-track-forward all -- [anywhere]/0 [anywhere]/0

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ufw-before-logging-output all -- [anywhere]/0 [anywhere]/0
ufw-before-output all -- [anywhere]/0 [anywhere]/0
ufw-after-output all -- [anywhere]/0 [anywhere]/0
ufw-after-logging-output all -- [anywhere]/0 [anywhere]/0
ufw-reject-output all -- [anywhere]/0 [anywhere]/0
ufw-track-output all -- [anywhere]/0 [anywhere]/0

Chain ufw-after-forward (1 references)
target prot opt source destination

 

Chain ufw-after-input (1 references)
target prot opt source destination
ufw-skip-to-policy-input udp -- [anywhere]/0 [anywhere]/0 udp dpt:137
ufw-skip-to-policy-input udp -- [anywhere]/0 [anywhere]/0 udp dpt:138
ufw-skip-to-policy-input tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:139
ufw-skip-to-policy-input tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:445
ufw-skip-to-policy-input udp -- [anywhere]/0 [anywhere]/0 udp dpt:67
ufw-skip-to-policy-input udp -- [anywhere]/0 [anywhere]/0 udp dpt:68
ufw-skip-to-policy-input all -- [anywhere]/0 [anywhere]/0 ADDRTYPE match dst-type BROADCAST

Chain ufw-after-logging-forward (1 references)
target prot opt source destination
LOG all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix "[UFW BLOCK] "

Chain ufw-after-logging-input (1 references)
target prot opt source destination
LOG all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix "[UFW BLOCK] "

Chain ufw-after-logging-output (1 references)
target prot opt source destination

Chain ufw-after-output (1 references)
target prot opt source destination

Chain ufw-before-forward (1 references)
target prot opt source destination
ACCEPT all -- [anywhere]/0 [anywhere]/0 ctstate RELATED,ESTABLISHED
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 3
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 11
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 12
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 8
ufw-user-forward all -- [anywhere]/0 [anywhere]/0

Chain ufw-before-input (1 references)
target prot opt source destination
ACCEPT all -- [anywhere]/0 [anywhere]/0
ACCEPT all -- [anywhere]/0 [anywhere]/0 ctstate RELATED,ESTABLISHED
ufw-logging-deny all -- [anywhere]/0 [anywhere]/0 ctstate INVALID
DROP all -- [anywhere]/0 [anywhere]/0 ctstate INVALID
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 3
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 11
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 12
ACCEPT icmp -- [anywhere]/0 [anywhere]/0 icmptype 8
ACCEPT udp -- [anywhere]/0 [anywhere]/0 udp spt:67 dpt:68
ufw-not-local all -- [anywhere]/0 [anywhere]/0
ACCEPT udp -- [anywhere]/0 ***.***.***.*** udp dpt:5353
ACCEPT udp -- [anywhere]/0 ***.***.***.*** udp dpt:1900
ufw-user-input all -- [anywhere]/0 [anywhere]/0

 

Chain ufw-before-logging-forward (1 references)
target prot opt source destination

Chain ufw-before-logging-input (1 references)
target prot opt source destination

Chain ufw-before-logging-output (1 references)
target prot opt source destination

Chain ufw-before-output (1 references)
target prot opt source destination
ACCEPT all -- [anywhere]/0 [anywhere]/0
ACCEPT all -- [anywhere]/0 [anywhere]/0 ctstate RELATED,ESTABLISHED
ufw-user-output all -- [anywhere]/0 [anywhere]/0

Chain ufw-logging-allow (0 references)
target prot opt source destination
LOG all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix "[UFW ALLOW] "

Chain ufw-logging-deny (2 references)
target prot opt source destination
RETURN all -- [anywhere]/0 [anywhere]/0 ctstate INVALID limit: avg 3/min burst 10
LOG all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix "[UFW BLOCK] "

Chain ufw-not-local (1 references)
target prot opt source destination
RETURN all -- [anywhere]/0 [anywhere]/0 ADDRTYPE match dst-type LOCAL
RETURN all -- [anywhere]/0 [anywhere]/0 ADDRTYPE match dst-type MULTICAST
RETURN all -- [anywhere]/0 [anywhere]/0 ADDRTYPE match dst-type BROADCAST
ufw-logging-deny all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 10
DROP all -- [anywhere]/0 [anywhere]/0

Chain ufw-reject-forward (1 references)
target prot opt source destination

Chain ufw-reject-input (1 references)
target prot opt source destination

Chain ufw-reject-output (1 references)
target prot opt source destination

Chain ufw-skip-to-policy-forward (0 references)
target prot opt source destination
DROP all -- [anywhere]/0 [anywhere]/0

Chain ufw-skip-to-policy-input (7 references)
target prot opt source destination
DROP all -- [anywhere]/0 [anywhere]/0

Chain ufw-skip-to-policy-output (0 references)
target prot opt source destination
ACCEPT all -- [anywhere]/0 [anywhere]/0

Chain ufw-track-forward (1 references)
target prot opt source destination

Chain ufw-track-input (1 references)
target prot opt source destination

Chain ufw-track-output (1 references)
target prot opt source destination
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 ctstate NEW
ACCEPT udp -- [anywhere]/0 [anywhere]/0 ctstate NEW

Chain ufw-user-forward (1 references)
target prot opt source destination

 

Chain ufw-user-input (1 references)
target prot opt source destination
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable
REJECT all -- ***.***.***.*** [anywhere]/0 reject-with icmp-port-unreachable

...... followed by a lot of rejects of this kind and then .....

ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:20
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:21
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:22
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:25
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:53
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:80
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:110
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:143
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:443
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:465
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:587
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:993
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:995
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:3306
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:8080
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:8081
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:10000
ACCEPT udp -- [anywhere]/0 [anywhere]/0 udp dpt:53
ACCEPT udp -- [anywhere]/0 [anywhere]/0 udp dpt:3306
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 tcp dpt:25
ACCEPT udp -- [anywhere]/0 [anywhere]/0 udp dpt:25
ACCEPT tcp -- [anywhere]/0 [anywhere]/0 multiport dports 20520:20620

Chain ufw-user-limit (0 references)
target prot opt source destination
LOG all -- [anywhere]/0 [anywhere]/0 limit: avg 3/min burst 5 LOG flags 0 level 4 prefix "[UFW LIMIT BLOCK] "
REJECT all -- [anywhere]/0 [anywhere]/0 reject-with icmp-port-unreachable

Chain ufw-user-limit-accept (0 references)
target prot opt source destination
ACCEPT all -- [anywhere]/0 [anywhere]/0

Chain ufw-user-logging-forward (0 references)
target prot opt source destination

Chain ufw-user-logging-input (0 references)
target prot opt source destination

Chain ufw-user-logging-output (0 references)
target prot opt source destination

Chain ufw-user-output (1 references)
target prot opt source destination

 

That is nice. Making it very hard to see which lines in the log are relevant to the e-mail to be sent. Most of the lines in your pasted log are other servers trying to send to your e-mail server, so they are quite useless in resolving your problem. You could make some effort and only paste log entries relevant to the e-mail being sent, since you know what e-mail address the e-mail is sent to and can find it in the log.
Just guessing here, but is this the email you tried to send:

That e-mail is suspended and is now in mailq. What shows command (run as root)

Code:

mailq 

 

I'm sorry for this inconvenience, I hope you forgive.

Ok, the mailq log shows for this specific sending:

752A3A07116 3943 Mon Dec 23 19:12:13 [email protected]
(connect to mx01.emig.gmx.net[212.227.17.5]:25: Connection timed out)
[email protected]

The "[email protected]" address was not involved in the sending. I don't know, why it came up. It is the Outlook 365 email-address of myself. But it installed in my Outlook, of course, from which I sent the test mail. But I sent the testmail with the senders-email account emailbox in office not with the "[email protected]" one.

 

Looks like e-mail servers for gmx.at do not listen on port 25. So they can not work as receiving e-mail servers. I do not know why, contact gmx.at for that.
You can test yourself with

Code:

telnet mx00.emig.gmx.net 25

To make sure your e-mail server is set up propely, test with https://www.mail-tester.com/

 

That cannot be, could it?:

752A3A07116 3943 Mon Dec 23 19:12:13 [email protected]
(connect to mx00.emig.gmx.net[212.227.15.9]:25: Connection timed out)
[email protected]

Even mail-tester cannot receive emails from this domain.
But Gmail CAN! Why? That's really embarrasing.

 

And 2 days ago, everything was working fine. As I said, the only thing I changed, was the server-name/domain of the dedicated webserver.

 

is your SPF correct? MXtoolbox shoud be able to check that also.
Otherwise, it looks a lot like your IP is blocked by those hosts since they refuse connections from your server.

 

Yes, thank you, there was a small flaw with the SPF - record, as the old server-domainname was in it. I corrected it, but it still doesn't work, although I have allowed it some time for updating the DNS entry in the network.

Maybe I have overlooked the old server-name somewhere else to. I will look through all possible locations and will update you here.

 

Could it be, that the mail providers request DNS-entries for the TLD of my server domain, too? I just made DNS entries for the Sub-Domain server.serverdomain.com and not for serverdomain.com. I will try to add them and see, if it makes a difference.

 

It's crazy, I tried everything now, adjusted the DNS entries to the same constellation, which was working with the old servername/domain, checked outlook 365 blocked IPs (server IP was not blocked anyhow) and when I send the other way round (from the emailadresses, which don't receive back to the email-addresses in question), it works too. But when I try to "answer" these emails, again, they are not received.

In Gmail, no problem from both sides.

I am really clueless by now.

 

Yep, that did the trick. The provider blocked my email ports in for my dedicated server in his firewall. He unblocked them and it started working.
And also I did optimize my DNS-entries.

But now, I got a different error: I had set up the server-domainname as an email-domain. The maillog said, this is not the best practice (as it also is a subdomain), so I deleted the email-box and the email-domain of it and now I cannot connect to the other accounts via IMAP. SMTP seems to be working. This email-stuff is driving me crazy. :-()

Maybe someone of you have got a clue, what this now could be.

 

If it works, why do you change it?

I can not see what is wrong with that. Do you perhaps mean server hostname?
For example, if I have e-mail server with hostname posti.taleman.ovh, I can have e-mail domain taleman.ovh. Nothing wrong or not best practice with that.

Is this the problem you now have? And the only problem? What happens when you try to connect? What other accounts?

 

Since I removed the server.servername.com as a Email-Domain, I cannot connect to the other domais with server.servername.com as Incoming and Outgoing server. But I can connect with webmail.

I supposed, it might have something to do with the SSL-DKIM. Because the server.servername.com - serverdomain had SSL/DKIM set up in DNS. So I tried to connect with the default ports, 143 (IMAP) and 25 (SMTP). Didn't work.

Then I tried to resetup the server.servername.com as an email-domain, now it doesn't even work with that (which had worked before).

I checked DNS and also didn't find it. So it must be a DNS problem :-|

I will try out some things and will keep you updated.

Thanks for your input and help so far.